5Department of Environmental Health Engineering, School of Public Health, Ilam University of Medical Sciences, Ilam, Iran

Abstract

Nowadays, one of the major environmental issues is air pollution due to industrialization and urbanization in the current century. The most important consequences of air pollution are cardiovascular and respiratory diseases. The aim of this study was to assess the incidence of hospital admissions for cardiovascular disease (HACVD) attributed to dust events in Abadan, Iran. Daily particulate matter data were used to assess the health impacts of human exposure to this pollutant. For this purpose, AirQ2.2.3 software, developed by the world health organization (WHO) European Center for Environment and Health, was applied. The results show that 6.9% (95% CI: 5.2-9.1%) of HACVD in Abadan were attributed to dust events concentrations. Effort should be made by governmental authorities to control the dust hazard to inhabitants by spreading mulch, the management of water bodies, decreasing emission of air pollutants from their sources, development of green space and the planting of some new species of plants.

Introduction

Air pollution due to industrialization and urbanization is one of the major environmental issues in the current century (1-6). According to the World Health Organization (WHO) report (7, 8), 800,000 people die globally each year from cardiovascular and respiratory diseases resulting from air pollution and about 150,000 of these deaths occur in southern Asia (9, 10). Epidemiological studies have showed that chronic and acute health problems attributed to outdoor air pollution include hospitalizations, respiratory, cardiopulmonary and cardiovascular diseases and mortalities (11-15). Among ambient atmospheric pollutants, particulate matter (PM) is one of the pollutants with highly undesirable and harmful outcomes for human health (12, 16-17). Many studies have reported strong statistical association between PM and respiratory diseases, and pulmonary damage and mortality among populations. PM10 is a fraction of particulate matter with an aerodynamic diameter equal to or less than 10μm (18-19). Short-term exposure to PM10 can bother the lungs and possibly cause immune responses, lung constriction, shortness of breath and cough. Long-term exposure to PM10 may result in cancer and premature mortalities (20-21). In addition to the health outcomes due to industrialization and urbanization, natural dust events have affected various geographical areas in recent years, especially the Middle Eastern countries (1). The regions of southwest of Iran have been exposed to Middle Eastern Dust (MED) storms, especially those coming from the Arabian Peninsula, Kuwait and Iraq. Abadan city is located in the west of Iran, and has been exposed to large amounts of PM10 as a result of MED events (2-3, 20-21). Shahsavani et al. (2012) showed that high concentrations of particulate matter led to adverse outcomes for human health during dust event days in Ahvaz, Iran (22). For comparison, Kwon et al. (2002) argued that there is a statistically significant correlation between dust storms and death associated with cardiovascular and respiratory diseases in Seoul, Korea (23), while Meng and Lu (2007) evaluated the relationship between dust events and hospital admissions due to respiratory and cardiovascular diseases, pneumonia, and hypertensions in China (24).

The main objective of this study was to estimate the health effects of Middle-Eastern Dust (MED) storms on the general population in Abadan using AirQ2.2.3 model in 2015.

Materials and Methods

This cross-sectional study was performed to investigate the hospitalizations for cardiovascular disease attributed to dust events in Abadan, Iran during 2015.

Study area

Abadan (30°20ʹN, 48°17ʹE), with a population of more than 300,000 individuals, is one of the metropolitans in Khuzestan province (25). Location of Abadan in the southwest of Iran (Fig. 1).

Air sampling

PM10 concentrations were measured using the Beta attenuation method. One-year data of PM10 levels in 2015 were collected.

Health impacts

AirQ2.2.3 software was used to determine the effects of short-term exposure to air pollutants on the health of people living in a certain time and region. In epidemiological studies, particularly in AirQ, the main parameters related to health are relative risk (RR) and baseline incidence (BI). The RR is the possibility of developing a sickness resulting from contact with a pollutant (Table 1). The values of relative risk and baseline incidence have been accepted from data files of the AirQ2.2.3 software developed by the WHO European center for environment and health based on various conducted peer-reviewed studies (26-28). In this software, the health impact assessment of air pollutants is achieved by calculation of the attributable proportion (AP), which explains the portion of health impacts that occur for certain people due to contact with air pollutants. The AP can be calculated by the following equation:

where AP and RR (cc) are the attributable proportion of the health impact and relative risk for a certain health impact in the group c of exposure. Also, P (c) is the fraction of the target population in group c of exposure.

The amount attributable to the population exposure is calculated by the Equation (2), if the baseline frequency of the health effect in the studied population is clear.

IE=I×AP (2)

where IE and I are the rate of the health impact attributable to the contact and the baseline frequency of the health impact in the population respectively. Finally, consid­ering the population size, the total number of excess cases attributable to the exposure is specified by Equation (3).

NE=IE×N (3)

where NE is the number of persons attributed to the exposure and N is the total number of evaluated residents. The mean daily concentrations of PM10 were used in the study. Finally, the numbers of individuals for hospital admissions due to cardiovascular diseases (HACVD) and respiratory diseases (HARD) were estimated by RR and BI using the AirQ2.2.3 model.

Results and Discussion

Health impact assessment

Table 1 shows the relative risk (95% CI) and baseline incidence used for investigating the health effects of PM10 in Abadan during 2015. The maximum RR related to PM10 in Abadan, with value of 1.009 was obtained for HARD.

The annual average PM10 concentration based on report National Ambient Air Quality Standard (NAAQS) is 150μg/m3. This higher increase of PM10 in Abadan can be due to greater exposure of this city to Middle Eastern Dust (MED) storms during the year from the arid areas such as Iraq and Saudi Arabia (22).

Health impact assessment

Table 2 shows, the number of excess cases for HACVD and HARD in BI=436 and 1260 that were estimated for Abadan to be 144 and 372 individuals respectively. The lower level of RR value can be achieved if some air pollution control strategies are used for reducing PM10 emissions. The hospitalizations due to respiratory diseases were 2675 cases in Ahvaz in 2012 (31), which shows decrease of about 1356 cases in HARD attributable to PM10 exposure.

For comparison, the number of excess cases of HARD and HACD due to exposure to PM10 were estimated in Tallinn (Estonia) to be equal to 71 and 204 individuals with the 95% confidence interval (CI) (32). In other studies, undertaken in China, a significant association between PM10 levels and HARD with a central relative risk of 1.14 (1.01-1.29) was observed, in which this health endpoint in the cold season was higher than the one in the warm season (2, 33). The study of short-term health effects of PM10 in Suwon indicated that the number of excess cases for the HARD and the HACD were 462 and 179 individuals respectively (30).

The number of excess cases of HACVD and HARD associated with PM10 concentrations during 2015 is presented in Figure 2. This figure illustrates diagrams based on the number of every health effect and the number of estimated cases at central RR (50%) versus PM10 concentration respectively. In Abadan, the number of 15.2 per 105 individuals of HACVD and 39.2 per 105 individuals of HARD can be attributed to the PM10 concentrations above 110 µg/m3, respectively. For each increase of 10 µg/m3 in concentration of PM10 the risks of HACVD and HARD rise about 0.8 and 0.9% respectively.

For comparison, in another study, undertaken in northern China, there was a 0.036% increase in HACVD and HARD for each 10 µg/m3 increase in the PM10 level (33). In the USA, each 10 µg/m3 increase of PM10 concentration up to 150 µg/m3 caused a 0.12% increase in the risk rate of mortality among inhabitants of San Jose during 1980-1986 (34). For PM10 lower than 100 µg/m3, each 10 µg/m3 increase of PM10 level led to a 1.1% increase in mortality risk in Los Angeles, USA (35). In another study in Egypt, an increase of 4.1% in the HARD was associated with an increase of 10 µg/m3 in PM10 level (36).

In a cohort study in 25 cities of China, the researches indicated that 1.8% (95% CI: 0.8-2.9%) and 1.7% (95% CI: 0.3-3.2%) increase of mortality risk were related to a 10 µg/m3 increment of PM10 level for cardiovascular mortality and respiratory mortality respectively (37).

These results can be attributed to the varying geographic conditions, population ratios, climates, and the rates of development of these cities. Furthermore, Abadan, located in a desert area and more subjected to MED storms, has a higher value of AP, and so this subjects the population to a greater exposure so that the rate of hospitalizations is higher than in the other cities.

Conclusion

The results for the assessment of health impacts of particulate matter (PM10) exposure showed that MED storms are the main cause of dust events in Abadan. The results also indicated that the AirQ model is an effective, helpful and easy tool to determine health impacts of PM10. Considering the cardiovascular and respiratory mortalities associated with PM10, it can be concluded that cardiovascular mortality had the main role in the total mortality resulting from particulate matter. In order to diminish the health effects of particulate matter, health training should be conducted to encourage the public, especially people with chronic lung and heart diseases, the elderly, and children to reduce their activities on the dusty days. Moreover, efforts should be made at the governmental scale to control dust entering the country by spreading mulch and the development of green space is essential.

Acknowledgments

The authors would like to thank Student Research Committee, Abadan School of Medical Sciences for providing financial supported by the grant: (IR.ABADANUMS.REC.1396.202) of this research.

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